DPI vs PPI – Image Resolution Explained
DPI (dots per inch) and PPI (pixels per inch) are often used interchangeably, but they measure different things. Getting them confused leads to blurry prints and unnecessarily large files.
The distinction
| PPI | DPI | |
|---|---|---|
| What it measures | Pixels in a digital image | Ink dots a printer lays down |
| Where it's set | In the image file metadata | In the printer driver/settings |
| Affects file size? | Yes — more PPI = larger file (if resized) | No — only affects print quality |
| Screen resolution | Relevant | Not applicable |
| Print quality | Determines detail in output | Determines sharpness printer can achieve |
Standard values to know
- 72 PPI — historic web standard (from old Mac monitors). Modern screens vary widely; this number means little today
- 96 PPI — Windows screen default reference point
- 300 PPI — print standard for photos and professional documents
- 150 PPI — acceptable for large-format banners viewed from a distance
- 600+ DPI — typical laser printer resolution
- 1200–4800 DPI — photo printers and inkjets at high quality
Practical rule
For web: resolution metadata (PPI) doesn't affect screen display — only pixel dimensions matter. A 1000×1000px image looks the same at 72 PPI or 300 PPI on screen. For print: export at 300 PPI at the final print size. A 4×6 inch print at 300 PPI needs 1200×1800 pixels minimum.
Frequently Asked Questions
Should I save web images at 72 or 96 PPI?
It doesn't matter — browsers ignore PPI metadata. Only pixel width × height affects screen display and file size.
My photo is 300 PPI but prints blurry — why?
The pixel dimensions are too low. A 300×300px image at 300 PPI only prints 1×1 inch. You need 300 × print-inches pixels in each dimension.
How do I change PPI without changing quality?
Change PPI in metadata only (not resampling) — this changes the intended print size without affecting actual pixel data or quality.